Cold temperatures in Montana and North Dakota

February 8th, 2019 |

GOES-16

GOES-16 “Clean” Infrared Window (10.3 µm) images, with hourly plots of surface reports [click to play animation | MP4]

Very cold surface air temperatures occurred in northeastern Montana and northwestern North Dakota on the morning of 08 February 2019 — with official lows of -50ºF near Antelope and Four Buttes in Montana and -47ºF at Bottineau in North Dakota (and according to MesoWest, -49ºF was registered at a Department of Transportation site west of Crosby in far northwestern North Dakota). GOES-16 (GOES-East) “Clean” Infrared Window (10.3 µm) images (above) revealed surface brightness temperatures across those areas were as cold as -47ºC (-53ºF).

A sequence of VIIRS Infrared Window (11.45 µm) images from Suomi NPP and NOAA-20 (below) showed similar surface brightness temperatures, with some pixels as cold as -48ºC (-54ºF). The color enhancement applied to the VIIRS images is the same as that used on the GOES-16 images above, with the red colors beginning at the -40ºC breakpoint (violets begin at -50ºC). While there is not a direct correspondence between satellite-sensed surface infrared brightness temperatures and air temperatures measured in an above-ground instrument shelter, with improving satellite spatial resolution the difference is often within 1-3ºC (or 2-5ºF).

VIIRS Infrared Window (11.45 µm) images from Suomi NPP (at 0753 and 0937 UTC) and NOAA-20 (at 0844 UTC) [click to enlarge]

VIIRS Infrared Window (11.45 µm) images from Suomi NPP (at 0753 and 0937 UTC) and NOAA-20 (at 0844 UTC) [click to enlarge]



Cloud-top waves producing turbulence north of Hawai’i

February 6th, 2019 |
GOES-17 Low-level (7.3 µm), Mid-level (6.9 µm) and Upper-level (6.2 µm) Water Vapor images [click to play MP4 animation]

GOES-17 Low-level (7.3 µm), Mid-level (6.9 µm) and Upper-level (6.2 µm) Water Vapor images [click to play MP4 animation]

* GOES-17 images shown here are preliminary and non-operational *

Transient pockets of cloud-top waves were evident on GOES-17 Low-level (7.3 µm), Mid-level (6.9 µm) and Upper-level (6.2 µm) Water Vapor images (above) north of Hawai’i on 06 February 2019. Some of the waves were located along the tops of convective cloud features, while others appeared to be randomly distributed.

Plots of rawinsonde data from Lihue, Hawai’i (below) showed that winds within the middle to upper troposphere had a general westerly component — so these mesoscale cloud-top wave features were oriented perpendicular to the flow.

Plots of rawinsonde data from Lihue, Hawai'i [click to enlarge]

Plots of rawinsonde data from Lihue, Hawai’i [click to enlarge]

There was only 1 pilot report of turbulence within the broad region exhibiting these waves, occurring at 2304 UTC at an altitude of 33,000 feet — and this appeared to coincide with a discrete wave packet that was propagating eastward (below).

GOES-17 Upper-level Water Vapor (6.2 µm) images within 30 minutes of the 2304 UTC pilot report of turbulence [click to enlarge]

GOES-17 Upper-level Water Vapor (6.2 µm) images within 30 minutes of the 2304 UTC pilot report of turbulence [click to enlarge]

While the more robust wave packets could also be seen in GOES-17 “Clean” Infrared Window (10.3 µm) images (below), their complete areal coverage was more obvious in the Water Vapor imagery — particularly where the wave features were more subtle.

GOES-17 Upper-level Water Vapor (6.2 µm) and “Clean” Infrared Window (10.3 µm) images at 2302 UTC [click to enlarge]

Aviation advisories for Significant Weather (SIGWX) had been issued for that region (below), which included a Moderate risk for Clear Air Turbulence (CAT) from 28,000-39,000 feet and the possibility of isolated/embedded Cumulonimbus (CB) clouds with tops to 38,000 feet, along with a west-northwest high-level jet stream from 290º at 90 knots. The pilot report of turbulence at 33,000 feet included winds from 261º at 81 knots.

GOES-17 Upper-level Water Vapor (6.2 µm) image, with plots of aviation Significant Weather advisories [click to enlarge]

GOES-17 Upper-level Water Vapor (6.2 µm) image, with plots of aviation Significant Weather advisories that were in effect at that time [click to enlarge]

The cloud-top waves were also seen in a sequence of VIIRS Infrared Window (11.45 µm) images from NOAA-20 and Suomi NPP, viewed using RealEarth (below).

VIIRS Infrared Window (11.45 µm) images from NOAA-20 (at 2230 and 0030 UTC) and Suomi NPP (at 2320 UTC) [click to enlarge]

VIIRS Infrared Window (11.45 µm) images from NOAA-20 (at 2230 and 0030 UTC) and Suomi NPP (at 2320 UTC) [click to enlarge]

Cyclogenesis along the US East Coast

February 4th, 2019 |


The approach of an upper-tropospheric Potential Vorticity (PV) anomaly induced rapid cyclogenesis just off the US East Coast on 04 February 2019, with the surface low rapidly occluding (surface analyses). The eastward-propagating PV Anomaly was apparent on GOES-16 (GOES-East) Air Mass RGB images from the AOS site (below) as darker shades of orange — transitioning to shades of red as the tropopause descended to lower altitudes bringing more ozone-rich air from the stratosphere into the atmospheric column.

GOES-16 Air Mass RGB images [click to play MP4 animation]

GOES-16 Air Mass RGB images [click to play MP4 animation]

A sequence of Infrared Window images from Terra MODIS (11.0 µm) and NOAA-20/Suomi NPP VIIRS (11.45 µm) (below) showed the cyclone at various stages of development. The surface low passed over  the Cape Lookout, North Carolina buoy as it was intensifying, with winds gusting to 44 knots around 12 UTC (winds/pressure | peak wind gusts).

Infrared Window images from Terra MODIS (11.0 µm) and NOAA-20/Suomi NPP VIIRS (11.45 µm), with plot of fixed buoy reports [click to enlarge]

Infrared Window images from Terra MODIS (11.0 µm) and NOAA-20/Suomi NPP VIIRS (11.45 µm), with plots of fixed buoy reports [click to enlarge]

A similar sequence of Visible images from Terra MODIS (0.65 µm) and NOAA-20/Suomi NPP VIIRS (0.64 µm) (below) showed the cyclone during daylight hours.

Visible images from Terra MODIS (0.65 µm) and NOAA-20/Suomi NPP VIIRS (0.64 µm), with plots of fixed buoy reports [click to enlarge]

Visible images from Terra MODIS (0.65 µm) and NOAA-20/Suomi NPP VIIRS (0.64 µm), with plots of fixed buoy reports [click to enlarge]

===== 05 February Update =====

GOES-16

GOES-16 “Clean” Infrared Window (10.3 µm) images [click to play MP4 animation]

After the primary center of circulation began to weaken, a pair of residual lower-tropospheric vortices (surface analyses) was seen to persist on GOES-16 “Clean” Infrared Window (10.3 µm) images (above), rotating around each other in a binary interaction known as the Fujiwhara effect. The two vortices were also evident in NOAA-20 VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images at 0620 UTC (below) — in spite of the lack of illumination from a New Moon, airglow alone was sufficient to provide an impressive “visible image at night” with the Day/Night Band. (note: the NOAA-20 VIIRS images are incorrectly labeled as Suomi NPP)

NOAA-20 VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images at 0620 UTC [click to enlarge]

NOAA-20 VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images at 0620 UTC [click to enlarge]

During the early morning hours, an undular bore was evident on GOES-16 “Red” Visible (0.64 µm) images (below), moving toward the westernmost vortex. As the bore began to move over warmer waters of the Gulf Stream, it slowly dissipated.

GOES-16

GOES-16 “Red” Visible (0.64 µm) images [click to play animation | MP4]

Although not particularly intense, this slow-moving midlatitude cyclone was able to draw an appreciable amount of moisture northward from the tropics/subtropics as shown by the MIMIC Total Precipitable Water product (below).

MIMIC Total Precipitable Water product [click to play animation | MP4]

MIMIC Total Precipitable Water product [click to play animation | MP4]

Paper mill fire in New Jersey

January 30th, 2019 |

GOES-16 Near-Infrared

GOES-16 Near-Infrared “Snow/Ice” (1.61 µm, top), Near-Infrared “Cloud Particle Size” (2.24 µm, center) and Shortwave Infrared (3.9 µm, bottom) images, with hourly plots of surface observations [click to play animation | MP4]

1-minute Mesoscale Domain Sector GOES-16 (GOES-East) Near-Infrared “Snow/Ice” (1.61 µm), Near-Infrared “Cloud Particle Size” (2.24 µm) and Shortwave Infrared (3.9 µm) images (above) displayed thermal signatures from a large fire at the Marcal Paper Mill in Elmwood Park, New Jersey during the evening hours of 30 January 2019. The fire reportedly began around 2215 UTC or 5:15 PM local time — and during the subsequent hours, strong winds with very cold temperatures (falling to the single digits above zero F) in the wake of a cold frontal passage hampered the firefighting efforts. Note on the plots of surface observations that smoke (K) was reported immediately downwind of the fire at Teterboro Airport (station identifier KTEB) from 02 to 05 UTC.

The nighttime thermal signatures seen on the near-infrared 1.61 µm and 2.24 µm images (brighter white pixels) result from the fact that those two ABI spectral bands are located close to the peak emitted radiance of very hot features such as volcanic eruptions or large fires (below).

Plots of Spectral Response Functions for ABI Bands 5, 6 and 7 [click to enlarge]

Plots of Spectral Response Functions for ABI Bands 5 (1.61 µm), 6 (2.24 µm) and 7 (3.9 µm) [click to enlarge]

The thermal signature of the fire became less distinct in GOES-16 imagery after about 06 UTC, but was still well-defined in higher-resolution VIIRS Shortwave Infrared (3.74 µm) imagery (below) from NOAA-20 (overpass data acquired at 0614 and 0754 UTC) and Suomi NPP (overpass data acquired at 0704 UTC).

VIIRS Shortwave Infrared (3.74 µm) images from NOAA-20 (at 0614 and 0754 UTC) and Suomi NPP (at 0704 UTC) [click to enlarge]

VIIRS Shortwave Infrared (3.74 µm) images from NOAA-20 (at 0614 and 0754 UTC) and Suomi NPP (at 0704 UTC) [click to enlarge]